Engine balancer



June 15 1926.

A. B. GILBERT ENGINE BALANCER I 3 Sheets-Sheet 1 Filed May 25, 1924 INVENTOR. Ail a5 Gz'lberz BY 5; 5

I L4TTOR Y.

June 15 1926. 1,588,720 A. B. GILBERT ENGINE: BALANCER Filed May 25, 1924 3 Sheets-Sheet 2 l\ '1 q m w IN V EN IOR.

June 15 1926.

- 1,588,720 A. B. GILBERT ENGINE BALANCER 7 Filed May 23, 1924 3 Sheets-Sheet 5 g mun 30 IN V EN TOR.

Patented June 15, 1926.

UNITED STATES PATENT OFFICE.

ALVA B. GILBERT, OF TOLEDO, OHIO, ASSIGNOIR- TO THE WILLYS-OVERLAND COM- PANY, OF TOLEDO, OHIO, A CORPORATION OF OHIO.

ELIGINE BALANOER.

Application filed May 23, 1924. Serial No. 715,349.

This invention relates to improvements in engine balancers and has reference particularly to that class of balancers which are designed to counteract the vibrations set up in the engine by secondary inertia forces. A devicefor this purpose is illustrated in the patent to Lanchester 1,163,832, in which is employed a pair of rotating weights with the necessary driving connections. One object of the present invention is the provision of a simpler apparatus for accomplishing the same results.

Another object is the provision of meanswhich will permit the utilization of but one weight instead of two.

Further objects, and objects relatin to details ofconstruction and economies of manufacture, will appear as I proceed with the description of those embodiments of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawings, in which:

Figure I is a central, longitudinal, vertical section through a four-cylinder, internal combustion engine embodying one form of my invention.

Fig. II is a detail, transverse, sectional view taken substantially on the line IIII, Fig. I.

Fig. III is a transverse, sectional view corresponding to Fig. II, but showing a diflerent modification of the ihvention, and drawn to a larger scale. I

Fig. IV is a longitudinal, sectional view :tglien substantially on the line IV-IV, Fig.

Fig. V is a detail, partly in section, of a slightly modified form of weight which may be substituted for the weight illustrated in Fi III.

gimilar reference characters refer to like parts throughout the views.

Referring now more particularly to Figs. I and II, 10 is .a crankcase of an internal combustion engine having integral webs 11, 12 and 13, in which are located the front, center and rear bearings respectively, for a crankshaft 14:.

The engine illustrated is one having four cylinders,-but the application of the invention extends also to certain other types, as indicated in my co-pending application, Se-

rial Number 706,099, filed April 12th, 1924.-

Bolted to the bottom of the web 12'which on their inner sides, and the recesses are bridged by pins 24 and 25, in the nature of piston pins. These pins 24 and 25 are each Joined byvmeans of connecting rods 26 and 27 with the crank 23 of the shaft 20, so that the two weights move always in the same direction, although not necessarily at the same rate of speed.

Any convenient means may be employed to drive the shaft 22 at twice the speed of rotation of the shaft 14:. In the present instance, I have shown the shaft 22 extending into the forward end of the engine where 1t has a bearing in the web 11. On its forward end, it carries a gear 28 which meshes with a larger gear 29 secured upon the crankshaft 14, the number of teeth in the two gears being in the ratio of 1 to 2.

From an inspection of the diagrams in my co-pending application above referred to, it will be apparent that a single weight of proper mass, when caused to rec1procate with simple harmonic motionat double the speed of the crankshaft, w1ll accurately counter-balance the secondary 1nert1a forces of the engine. A single weight 18 or 19 of sufficient mass, when driven as shown in Figs. I and II, will approximate an accurate balancing of the secondary forces of the engine. There will, however, be a slight secondary force in the balancer itself, due to the same causes which produce a secondary force in the engine, and in order to eliminate such force, I' have divided the counter-balancing mass into two weights 18 and 19 and mounted both connecting rods on one crank, so that the-secondary forces of the two weights 18 and '19 counter-balance each other, and leave only the primary inertia forces of the combined mass to counter- In the modification illustrated in Figs. III, IV and V, the single balancing weight is not driven by a connecting rod, but by a means which produces in the weight, simple harmonic motion. Hence the weight has no secondary inertia force.

In Figs. IV and V, 12 is the central transverse web of the crankcase. Secured to the bottom of the web 12 by the usual studs 31 and nuts 32, is a combined bearing cap and bracket 33 carrying the lower half of the bushing 30, in which the crankshaft 14 revolves. The bracket 33 has twodownward extensions, as shown in Fig. IV, in which are located bearings 34 and 35 for a short shaft 36, having an eccentric portion 37 between the bearings and a gear 38 at one end. The extensions of the bracket 33 are preferably split horizontally by a plane bi-secting the bearings, the lower parts being secured to the upper by means of studs upon which are threaded nuts 39. Upon the lower part of one of these extensions of the bracket, there is a lip 40 which provides a cavity for the reception of oil into which the teeth of the gear 38 dip. The bracket 33 is drilled, as shown 'at 41 and 42, in order to convey lubricant from the crankshaft bearing to the bearings 34 and 35 of the shaft 36. The crankshaft 14 carries an integral flange 43 to which is bolted a ring gear 44 meshing with the gear 38. The gear 44 has twice as many teeth as the gear 38.

The eccentric portion 37 of the shaft 36 has bearing in a slide block 45 which is mounted to move between two ways or guides consisting of an upper member or bar 46 and a lower member or block 47. These two members are connected by means of stud bolts 48 and 49 which extend through spacers 50 and 51. A pin 52 or other convenient means may be employed to prevent the spacer 51 from turning on the bolt 49. Integral with the spacer 50 is an arm 53 which is pivoted at its outer end upon a trunnion 54 carried at the lower end of a bracket 55 which is secured to the web 12 by any suitable means.

The bolt 48 has a constricted portion, as shown in Fig. III, which, in combination with various drilled passages there illustrated, serves to carry oil under pressure from the trunnion 54 to the upper guide-way for the slide block 45. The latter also has a passage which registers regularly with the passage in bar 46, so as to carry oil to the bearings-between the slide block and the eccentric portion of the shaft.

The welglht shown in Fig. V is generally similar to t at in Fig. III. I have, however, shown the slide block split into two equal parts, 56 and 57, and the weight roper is made up of but twoelements, the rst being a block 58 cut away on its upper side to receive the eccentric and slide block, and the second being a bar 59 which is threaded to receive the threaded ends of stud bolts 60 and 61. The latter extend'through smooth bores in the block 58. Interposed between the block 58 and the heads of the bolts, are coil springs 62, which resiliently hold the various parts in close engagement; that is, they take up wear and maintain a nice fit between the sliding block sections 56, 57 and block 58 and bar 59, as well as between the same sections and the eccentric 37. In this way, I guard against any noise which might occur in the rapidly moving parts due to possible looseness of fit.

In designing a balancer of the type illustrated in Figs. III, IV and V the trunnion 54 should be mounted at a level such that the horizontal plane through its axis will bisect the arc of movement of the weight, and the weight should be of sufficient mass to permit the utilization of a relatively small arc in comparison to the distance from the center ofthe weight at its upper limit of motion. At this time the center of the eccentric is at point A. At its lowest extreme, the center of the eccentric is at point B. If an arc be struck between these two points with its center at the axis of the trunnion 54, the arc will be found to deviate from a straight vertical line to an almost imperceptible degree. In this manner, I obtain practically the same results as though I mounted the weight to slide in vertical guides, but by employing a pivot instead of guides, I eliminate a great deal of friction and wear, which are important matters when the speed of motion of the weights is taken into consideration. In its broader aspects, however, my invention comprehends any thing for holding the weights to a substantially vertical path of motion.

To those skilled in the art, the operation of the last described form of my invention, will be apparent without further explanation. The gearing is such that the weight moves up and down twice for every revolution of the crankshaft. Since it reciprocates with simple harmonic motion, it has only primary inertia forces, and these forces may be used to exactly counter-balance the secondary forces of the engine. The secondary force waves of the engine, have twice the frequency of the primary force waves, and the latter correspond to the speed of revolution of the crankshaft; hence the necessity for reciprocating the weight at twice crankshaft speed. For diagrams and a more detailed explanation of the theory of secondary force in engines, reference should be had to my co-pending application above-mentioned.

I claim as my invention:

1. In a reciprocating engine, a crankshaft, a second shaft rotating at twice crankshaft speed, a counter-balancing mass, and connections driven by said second shaft for no I causing reciprocations of the said mass at twice crank-shaft speed with simple harmonic motion in substantially a vertical line.

2.. In a reci rocating engine, a crankshaft, a second sha rotating at twice crankshaft speed, said second shaft having an eccentric portion, a counterbalancing mass arranged to be reciprocated by said eccentric portion in simple harmonic motion, and means for confining said reciprocations to substantially a vertical direction.

3. In a reciprocating engine, a crankshaft, an eccentric shaft driven at twice crankshaft speed, a weight provided with a horizontally movable slide, said slide having a bearing fitting an eccentric portion of the eccentric shaft, and means for confining the reciprocations of said weight to substantially a vertical direct-ion.

4. In areciprocating engine, a crankshaft,

a second shaft rotating at twice crankshaft speed, a balance weight, connections. driven by said second shaft-for reciprocating said weight withsimple harmonic motion in a .relatively short vertical path, and a pivot for said weight located to one side at a considerable distance comparatively from the center of mass of said weight.

5. In a reciprocating engine, a crankshaft,

ALVA B. GILBERT. 

